The Public Switched Telephone Network (PSTN) that has been the backbone of telephony communications for a century is transforming rapidly. Since the 1970s, the PSTN has been controlled through a set of signaling protocols called Signaling System #7 (SS7) developed by the International Standardization Sector (ITU-T) of the International Telecommunication Union (ITU). SS7 is also known variously as Common Channel Signaling System 7 (CCSS7), C7, Number 7 and CCIS7. The SS7 network manages the setup and teardown of telephone calls being placed from Plain Old Telephone Service (POTS) telephones through telephone exchange switches such as Digital Multiplex System (DMS) switches manufactured by Nortel Networks Corporation of Brampton, Canada.
In the past two decades, Voice over Internet Protocol (VoIP) technologies have been developed that directly compete with the well established POTS telephony system. In VoIP networks, telephone terminals are coupled to Internet Protocol (IP)-based networks, such as the Internet or private IP networks, and telephone calls are managed with the use of call processing servers, often called soft switches. The well-established protocol for use with voice or video calls over IP-based networks is called Session Initiation Protocol (SIP).
VoIP calls controlled by SIP and POTS calls controlled by SS7 each currently have advantages and disadvantages. VoIP calls utilize the non-dedicated nature of IP-based networks to transmit voice packets in efficient manners via a mesh of routers while POTS calls are dedicated connections via digitally switched circuits. This distinction typically provides operational cost advantages to VoIP (and hence lower prices) while also in some circumstances diminishing the quality and security of the VoIP telephone connection as compared to the traditional POTS connection.
Another significant distinction between the two telephony technologies is the flexibility that is often built into the soft switches and SIP used to manage the VoIP call as compared to the traditional telephone exchange switches, such as the DMS, and SS7 protocols. While a number of call service features were launched on the DMS (ex. call forward, call waiting etc.), the introduction of VoIP and its flexibility has led to significant developments in call service features. For example, web-based control of call routing which triggers multiple telephone terminals to ring simultaneously or in sequence is common within VoIP.
Despite the advantages of VoIP, a large portion of telephone consumers are remaining with POTS telephones. This is due to many factors including call quality, limitations on 911 services within VoIP and unwillingness to switch from the security of having a communication system in their home/office that has proven over time to be highly reliable, even during power outages. One downside to this reliance on POTS technology is that these consumers often cannot be offered new call service features that are available within VoIP systems. Further, in many circumstances, the call processing and management of the call features within POTS networks may cost the service provider more compared to similar call processing and call feature management within VoIP networks.
Against this background, there is a need for solutions that will mitigate at least one of the above problems, particularly enabling additional flexibility in call processing and/or call feature management within POTS telephone networks.